To anyone who doubts modern science still pursues essential lines of inquiry into the most pressing questions of our time, we present this resounding rebuttal. Two fearless truth seekers used lasers to figure out why fruit fly penises look weird.

"Look weird" is, of course, not a technical term. More specifically, the penises of Drosophilia feature a dizzying assortment of sharp hooks and spines. Not unlike snowflakes, no two sets of penile accessories are alike, meaning an expert biologist could tell which species a particular fruit fly belonged to based only on its genitalia.


Biologists have put forth a number of possible explanations as to why fruit fly penises possess these features, and none of these theories are for the squeamish. Some have suggested the males use the razor-sharp points on their penises as weapons, scrubbing out the sperm of any rivals that might have also tried to impregnate its mate. Another idea holds that the fruit fly uses the barbs to pierce a shortcut through the female's genitals, allow its sperm speedier access to the ova. A third theory is that the sharp points are just meant to injure the female, although no one can come up with a sensible reason why that would be advantageous.

To figure this out, biologists Michael Polak and Arash Rashed decided to remove the spines from some Drosophilia penises, so that they could observe what happened when a male tried to mate without them. Since the hooks were far too small to remove by hand, they elected to use a laser, which allowed them to shave off the millimeter-long barbs and hooks.


What happened next will, if there is any justice in the world, live on in the annals of scientific lore, right alongside Einstein formulating special relativity or Galileo first turning his telescope to the heavens:

They found that a partial shave did nothing, but the full treatment significantly reduced the odds of the males mating with females. With the spines, they were virtually guaranteed to mate if a female was around; without them, their chances fell to around 20%. It wasn't for lack of trying either - all of the shorn males tried to woo a female and almost all tried to mate. They simply failed. They did all the right things - mounting, placing their genitals in the right place - but it was for nought. And if the spineless males were placed in direct competition with a normal one over a female, they almost always lost.


And so the mystery is solved. It should be noted that Charles Darwin actually figured this all out 139 years ago, when he suggested pretty much exactly what Polak and Rashed discovered - that the male fruit flies would need these appendages to hold their mate securely during the ten minutes required for fruit fly copulation. Just more proof that it never pays to doubt Darwin - the man knew of what he spoke.

[Not Exactly Rocket Science]


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